Switch statement uninitialized variable

Question

The following code gives me: The local variable str may not have been initialized

 public class experiment{ public static void main(String[] args){ int day = 1; String str; switch (day) { case 1 : str = "nice"; break; } System.out.println(str); } } 

So, I gave str a null and it worked, but I'm still wondering why one of the documents works without initializing the value in the first place, I checked the triple, and I don't think I have typos:

 public class SwitchDemo { public static void main(String[] args) { int month = 8; String monthString; switch (month) { case 1: monthString = "January"; break; case 2: monthString = "February"; break; case 3: monthString = "March"; break; case 4: monthString = "April"; break; case 5: monthString = "May"; break; case 6: monthString = "June"; break; case 7: monthString = "July"; break; case 8: monthString = "August"; break; case 9: monthString = "September"; break; case 10: monthString = "October"; break; case 11: monthString = "November"; break; case 12: monthString = "December"; break; default: monthString = "Invalid month"; break; } System.out.println(monthString); } } 

Answer 1

Because the switch example in the sample documentation has a default statement. It is called if there is no other case . In your own code you do not have such a "backup".

Therefore, there always exists at least one called statement that will always initialize monthString .